390 On ihe Movements of' Camphor upon Water, 
in a late number of the Journal de Pharmacie. We shall ex- 
tract from it at present only the parts which relate to the sub- 
ject of this article. 
On the Motions of Alloys (f Potassium in contact with Water. 
A fragment of potassium thrown upon water, turns and 
agitates itself at the surface like a piece of camphor ; but a 
fragment of the alloy, which, being heavier than water, falls to 
the bottom, does not lead us to anticipate similar motions. M. 
Serullas, however, observed one of the fragments moving 
under water in a circular direction ; and he remarked that its 
progress was always opposite to that part of its surface from 
which the greatest quantity of hydrogen was disengaged, — a re- 
sult which he presumed was analogous to that which Benedict 
Prevost ascribed to the effluvia of camphor, and confirmed his 
opinion in opposition to that of Venturi, Carradori and others. 
In order to examine this point, M. Serullas threw some of 
the alloy, cparsely pulverised, into a mercurial bath, cover- 
ed with a slight film of water. All these particles, from 
the variety of their forms, the separation more or less complete 
of the metallic laminae which composed them, and which per- 
mitted the water to penetrate more or less readily, instantly 
assumed different motions, more energetic and more varied than 
those of camphor, but leaving no doubt respecting the analogy of 
the cause which produced them. In the case of camphor, says 
M. Serullas, it is an effluvium of its own substance, and in the 
case of the alloy, it is an effluvium of hydrogen ; and in both in- 
stances the motion is impaired by the resistance which the 
effluent matter experiences in the media into which it is pro« 
jected. 
M. Serullas observed, that in proportion as the potassium of 
the alloy was converted into potash, the debris of the antimony 
and of the carbon formed at the surface of the bath a species 
of black unctuous coating, which restrained the motions of the 
undecomposed fragments. He found, however, that they re- 
sumed their wonted vivacity by removing this pellicle ; and in 
order to put into full activity those which had become station- 
ary, and were not exhausted of their potassium, he had only to 
break them in pieces. 
